An imager in CMOS technology comprises a matrix of photosensitive pixels produced in an active layer, generally of weakly boron-doped silicon. The interconnections used to control the pixels are produced above the active layer by conductive tracks on a number of metal levels. With the matrices of pixels having an increasingly smaller pitch, the interconnect network, which is opaque, increasingly masks the light reaching the photosites of the pixels in a conventional “front-side” imager.
A “back-side” imager is designed for the light to reach the photosites through the face opposite the interconnect network, such that the interconnect network no longer contributes to reducing the quantity of light reaching the photosites.
This imager structure can however present drawbacks in certain applications.